Inertial navigation supplements satellite navigation, especially when satellite signals are weak or obstructed. A global navigational satellite system (GNSS) receiver in a car or truck may have difficulty producing accurate position and velocity estimates near tall buildings or in tunnels, for example.
Many vehicle navigation systems receive sensor inputs from the vehicle in which they are installed. A common example is wheel rotation information sensed at a vehicle wheel and transmitted over a vehicle information bus. However, in some cases it is desirable for a navigation system to be “cordless”; i.e. not to have to rely on a connection to vehicle-supplied information.
One prior art solution (“Cordless inertial vehicle navigation”, U.S. Pat. No. 8,406,996) relies on inherent motion constraints of cars and trucks, and uses self-contained barometric altimeter measurements as an input to a navigation filter. That system ignores roll rates, lateral acceleration and vertical acceleration. Despite the success of that approach, further improvements are possible and often desirable for high performance cordless inertial navigation.